The effect of nutrient intake from milk or milk replacer of pre-weaned dairy calves on lactation milk yield as adults: a meta-analysis of current data.

MedLine Citation:

PMID:
23296823
Owner:
NLM
Status:
Publisher

Abstract/OtherAbstract:

Data from calf studies conducted over the past 20 yr has shown that pre-weaning nutrient intake, from milk or milk replacer, can have profound effects on development of the calf that enhance first lactation and lifetime productivity. Many of the studies show positive but not significant effects of pre-weaning nutrition on long-term productivity, primarily due to a lack of power, usually due to inadequate animal numbers per treatment. Meta-analyses were conducted using Comprehensive Meta-Analysis software (CMA, v2.2.064, Biostat, Englewood, NJ; Borenstein et al., 2005) was used to evaluate the effects of pre-weaning nutrient intake and pre-weaning average daily gain (ADG) on first lactation milk production from studies where milk yield and pre-weaning treatment data were adequately described. Currently, twelve studies have been reported, describing milk yield of calves that had been fed various levels of pre-weaning nutrients, from both milk and milk replacer, and eleven evaluated the effect of pre-weaning ADG on long-term productivity. The estimated effect size for treatment (level of milk or milk replacer intake) and ADG were calculated. Using a random effects model, the overall milk yield response based on treatment was 435 ± 117 kg/lactation (P < 0.001), demonstrating that among the data sets milk yield in the first lactation was increased by increasing nutrient intake from milk or milk replacer in pre-weaned calves. Meta regression of the effect of ADG resulted in the following equation: milk yield = -106 kg + 1,551.4 kg × ADG (kg/d) (P = 0.01) indicating that for every kg of pre-weaning ADG, first lactation milk yield increased by 1,550 kg. Further, the meta-analysis yielded an odds ratio of 2.09 (P = 0.001) indicating that calves fed for greater pre-weaning ADG were two times more likely to have greater milk yield in the first lactation. Finally, the 2001 Dairy NRC calf model was used to estimate the difference, within study, of intake over maintenance from milk replacer, using either the actual data or the published ADG; the difference in intake over maintenance was used as a predictor in a meta-regression and resulted in the following equation: milk yield = -60 kg + 1,100 kg × estimated difference in intake over maintenance (P = 0.02). The data demonstrate that nutrient intake from milk or milk replacer during the pre-weaning period positively impacted long-term productivity of dairy calves and provides new management opportunities to improve milk yield of dairy cattle. These data appear to indicate that there are significant developmental functions being programmed in the neonatal calf that require further investigation.